Blaupunkt car amplifier

[Dobermann]

Hello brothers, i'm Dimitris from Athens (Greece) and i have a car audio amplifier: Blaupunkt GTA4 Special and i want lift up the output power in bridge mode. that amp give's 170wRMS/4Ù per channel (bridge mode) and that power is too little for my 2 subwoofers (250wRMS 500wMAX 4Ù / each sub). i want 270-280wRMS per channel (in bridge mode) (if is possible),
i was thinking to change the mosfets on power supply and output transistors, but i'm not sure for that... anything ideas??

Photos of amplifier:
Amplifier

[bawang]

Dimitris, first, before you do anything, be absolutely sure that you DO need the 270W/ch...... Assuming that you are not involved in those crazy SPL competitions, where volume matters over everything else, I am doubtful you'll ever need more than 100W RMS/ch in normal listening.

In order to modify your current amp to the power levels that you want, you might as well change the amp, as increasing the power level by that amount will involve changing/upgrading/adding (almost) all components; power supply, output drivers, output devices NOT to mention cooling requirements!

Or get an amp specifically designed for subwoofers, these amps are NOT linear amps, but they are Class D or T (or whatever their manufacturer calls them) where the cooling requirements are MUCH less, much higher efficiency and therefore more compact.

Still need the 270W RMS/ch?

[Dobermann]

yeah my friend.. i know that is so crazy but i want a DIY ampilifer at 2x270wRMS or a monoblock amp at 650wRMS at 2Ù.. can i take the chassis of this amp and change the PCB? i meen, another PCB of power supply and output...

[bawang]

Very ambitious plan, Dimitri. Technically, there is no reason why you can't take just the chassis of this amp and install the amp of your own design's PCB inside, provided the space is sufficient. But why waste a working amp?

Also, if we are talking about a Class B amp, a 2 x 270W RMS at 4 ohms amp is still a large amp, with large power requirements. And yet you still want it to be bridgeble into 2 ohms, my oh my..... you are looking at a serious output stage which can handle the current.... Not to mention a HUGE power supply. Search this forum for a SMPS and a high power amp and you may be able to modify it to suit.....

Good luck in your pursuit....

[Eva]

Even the heatsink is too weak for your purpose, so forget about modifying that amplifier. Start from scratch instead, your amplifier employs very simple electronics so you could just copy it in a scaled up fashion.

[Dobermann]

that is crazy idea right? that amp is Class AB not Class B... i know is very simple, but i was thinking to do something with that amp... well the output power is 170wRMS in bridge mode per ch. in stereo mode is 55w/4ohm - 82w/2ohm.. that amp what upgrades is need to deliver >240-250wRMS/4ohm in bridge mode (with 0.1-1THD)? i'm not sure to do that upgrades, just i ask to take ideas...

i'm DIY man so i love do myself the sound systems

[RogerGustavsson]

From 170 to 240 W, it is only 1.5 dB. Will not be worth all the trouble. Are your sure you are running the amplifier near clipping today? If not, I do not see the point.

[Dobermann]

this amp is clipping all the time.. u know, the each sub is 250wRMS and the amp is 170wRMS per ch.. my ideas is: with stronger mosfets (BUK456 or IRFZ44N), output transistors (BD250,BD249 or 2SA1216,2SC2922), bigger transformer and bigger capacitors on power supply i can get more output power. but i'm not sure...